hence the very
terms of each proposition are equivocal; and the possible length of some
of the intervals is so vast, that to affirm that all the chains raised
in such intervals were _contemporaneous_ is an abuse of language.

In order to illustrate this argument, I shall select the Pyrenees as an
example. Originally M. E. de Beaumont spoke of this range of mountains
as having been uplifted suddenly (_a un seul jet_), but he has since
conceded that in this chain, in spite of the general unity and
simplicity of its structure, six, if not seven, systems of dislocation
of different dates can be recognized.[246] In reference, however, to the
latest, and by far the most important of these convulsions, the chain is
said to have attained its present elevation at a certain epoch in the
earth's history, namely, between the deposition of the chalk, or rocks
of about that age, and that of certain tertiary formations "as old as
the plastic clay;" for the chalk is seen in vertical, curved, and
distorted beds on the flanks of the chain, as the beds _b_, fig. 11,
while the tertiary formations rest upon them in horizontal strata at its
base, as _c_, ibid.

The proof, then, of the extreme suddenness of the convulsion is supposed
to be the shortness of the time which intervened between the formation
of the chalk and the origin of certain tertiary strata.[247] Even if the
interval were deducible within these limits, it might comprise an
indefinite lapse of time. In strictness of reasoning, however, the
author cannot exclude the Cretaceous or Tertiary periods from the
possible duration of the interval during which the elevation may have
taken place. For, in the first place, it cannot be assumed that the
movement of upheaval took place after the close of the Cretaceous
period; we can merely say, that it occurred after the deposition of
certain strata of that period; secondly, although it were true that the
event happened before the formation of all the tertiary strata now at
the base of the Pyrenees, it would by no means follow that it preceded
the whole Tertiary epoch.

The age of the strata, both of the inclined and horizontal series, may
have been accurately determined by M. De Beaumont, and still the
upheaving of the Pyrenees may have been going on before the animals of
the Chalk period, such as are found fossil in England, had ceased to
exist, or when the Maestricht beds were in progress, or during the
indefinite ages which may have